I am getting following errors:

const validateOptions: ChildFormOptionProps
Argument of type 'number | undefined' is not assignable to parameter of type 'string'.
  Type 'undefined' is not assignable to type 'string'.ts(2345)

Here is my ts code : getting error at "parseInt(validateOptions.minlength)"

username: (control: AbstractControl): { [key: string]: ValidatorFn } | null => {
            const validateOptions = PatientFormService.controlProps['username'].options;
            if (Object.keys(validateOptions).length) {
                if (control.value && control.value.length < parseInt(validateOptions.minlength)) {
                    control.setErrors({ 'incorrect': true });
                    return control.errors;
                }
            }
            return null;
        },

any suggestion to fix this issue?

CodePudding user response：

You're calling parseInt, which accepts a string, with a value that has the type number | undefined. That's a type error, exactly what TypeScript is supposed to help you with. So what you need to do is modify the code so it doesn't try to use a number | undefined with parseInt (which makes no sense). For instance, you might add a guard for the undefined case, then either use the number as-is or, if you have some reason for ensuring it's an integer rather than fractional, use Math.round/ceil/floor as appropriate on it. For instance:

username: (control: AbstractControl): { [key: string]: ValidatorFn } | null => {
    const validateOptions = PatientFormService.controlProps['username'].options;
    if (Object.keys(validateOptions).length) {
        if (control.value &&
            validateOptions.minLength !== undefined &&          // ** Guard
            control.value.length < validateOptions.minlength) { // ** No parseInt
            control.setErrors({ 'incorrect': true });
            return control.errors;
        }
    }
    return null;
},

...but you may have to tweak that, I had to make a couple of minor assumptions in there.